Officials are probing how a 51-year-old highway bridge came to collapse in the Italian port city of Genoa yesterday, killing at least 26 people and injuring 16 others as it sent dozens of vehicles tumbling into a heap of concrete and twisted steel.

Boy dies after visit to Qld play centre

Police are calling for help from witnesses as they investigate the death of a three-year-old boy at a Queensland playground centre.

The child was found unresponsive at Inflatable World Toowoomba on Sunday afternoon.

He was discovered at the bottom of a slide with injuries to the back of his head and taken to Toowoomba Hospital, police say.

He was transferred to Brisbane's Lady Cilento Children's Hospital, where he died on Monday afternoon.

Child Protection Investigation Unit Detective Sergeant Brent Parker told the Toowoomba Chronicle the death was not being treated as suspicious, but urged people who were at the play centre around 1pm to speak to them.

"If anyone was around the under-5's section, particularly parents or adults that may have seen the child, is asked to talk to police," he told the paper.

Police are co-ordinating their investigation with Workplace Health and Safety.